Mon Prof Augmenté
Edge of the Visible Universe
Open to everyone until Saturday, October 3
To keep it, print it while it is open.
Light takes time to travel across space. Because of this, we can see only the part of the universe whose light has already reached us.
In the picture
- A nearby galaxy cluster: bright and detailed because its light has had a short journey.
- A middle-distance galaxy cluster: smaller and fainter because its light has traveled farther.
- A far galaxy cluster: barely visible at the limit of arriving light.
- A dark rim at the far edge: the boundary where arriving light fades from view.
Examples
- Seeing lightning before hearing thunder, because sound takes time to arrive.
- Looking at a distant city skyline at night, seeing light that left the buildings earlier.
Key takeaways
- Light from distant objects takes time to reach us.
- The observable universe is limited by how far light has traveled since it could travel freely.
Carry on in the app
Three questions on this lesson, to check the idea stuck. Free in the app while the lesson is in the free week.
At least one new illustrated lesson every weekday for your child’s year, with its quiz and a reminder at 6:15 pm.
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